CONTRIBUTIONS TO BOTANY. 
47 
become accumbent on the radicle, which corresponds in direction 
with the line of the raphe. The radicle is consequently trans- 
verse as regards the axis of the capsule, being neither centrifugal 
nor centripetal, but horizontal and parallel to a diametral line 
drawn across the axis of the fruit, and its free extremity points 
to a small hilum on the integument. 
From these facts it is clear that, generally, the seeds of Big- 
noniacea are furnished with three distinct integuments. The 
broad wing is a real tunic, being part of an extremely lax testa, 
often enlarged to ten times the diameter of the intermediate 
coriaceous coating, its sides becoming agglutinated together by 
pressure into the form of a delicate wing : it is proved to be the 
real testa by the passage of the cord of the raphe through its 
tissue along its ventral face, which cord does not enter into the 
substance of the second tunic until it pierces its way thi-ough 
it, in order to arrive at the chalaza of the inner integument. 
The intermediate, more or less coriaceous integument, with its 
very elongated, narrow neck, which is sometimes coiled up and 
free, and at other times hardened and adherent in the form of a 
septum, must be considered to be a development of the secun- 
dine, while the inner integument, with its mouth converted into 
a short sac, must be viewed as a product of the tercine ; it can- 
not be a very thin albumen, because it Jits too loosely upon the 
embryo, and because it is provided with a distinct chalaza. 
The few observations I have made relative to the structure of 
the carpels may not be uninteresting in this inquiry. Prof. 
DeCandolle, to whom we owe the best monograph of the family, 
has divided his ixihe Bignoniea into four subtribes; — 1. Eu~ 
bignoniecE, where the flattened and elongated capsule is 2-valved 
and opens by two sutures along the lateral margins, having the 
dissepiment parallel to the valves, which separate from it, show- 
ing numerous imbricated seeds attached to it, in one or more 
rows, near its two margins on both faces. This subtribe is 
again formed into divisions [Monostictides and Pleiostictides) , 
according to the number of series of seeds on each margin of the 
dissepiment. 2. Catalpea, where the capsule is also bilocular 
and bivalvular, but where the dissepiment lies across both valves 
at a right angle : the capsule here opens by two sutural lines, 
as in the preceding subtribe, and the dissepiment separates from 
the middle of the two valves; the seeds are attached to the dis- 
sepiment, as in the former case ; and the subtribe is again sub- 
divided in like manner, according to the number of series of the 
seeds. 3. Incarvillea, where the capsule has either one or two 
cells ; in the latter case, as in Amphicome, each cell opens by a 
simple suture, and the valves remain attached to the dissepiment, 
which is placentiferous in the axis on both faces ; in Incarvilleu 
